Apparatus for cleaning strip metal



Feb. 26, 1946. G. M. cRoFT Y APPARATUS FOR CLEANING STRIP METAL FiledMarch 20, 1940V 3 Sheets-Sheet l Feb. 26, 19416. G, M CRQFT 2,395,397

. APPARATUS FOR CLEANING STRIP METAL FiledvMarch 20, 1940 5 sheets-sheet2 i fl Fig 2 M WMW.

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APPARATUS FORCLEANING STRIP METAL Filed March 20, .w40 5 sheets-sheet 3Patented Feb. 26, 1946 UNITED] STATES PATENT OFFICE APPARATUS FORCLEANING STRIP METAL George M. Croft,

Pittsburgh, Pa., assgnor to Blaw-Knox Company, Pittsburgh, Pa., acorporation of New Jersey Application March 20, 1940, Serial No. 325,081

2 Claims.

This invention relates to the surface treating of strip metal, and isfor an apparatus for effectively cleaning the surface of a continuouslymoving strip by a `succession of alternate scrubbing and liquid sprayingoperations with rinsing and drying of the strip at certain stages in thetreatment.

In treating moving metal strip particularly y where the strip is to bemoved at a high rate of speed such as 1500 to 3000 feet per minute, itis apparent that even a few thousandths of an inch thickness of liquidlm on the surface of the strip will amount to a large quantity of liquidcarryover within a short period of time, thus emphasizing the need for apractical method of, in effect,

restricting each liquid treating step and preventparatus for cleaningmetal strip in which both mechanical scrubbing and chemical cleaning andfinal washing and drying are economically and effectively accomplished,and with practically no carry-over of chemical solutions used in onestage to another, and without the carry-over of appreciable amounts ofsolids on the surface of the metal resulting from the evaporation of alm`of such liquid. According to this invention, suction devices are usedat certain stages of the treatment in order to remove any adhering filmof liquid on the sheet, thereby avoiding the carryover of the liquid lmfrom one stage of the treatment to another, and also avoiding thedeposit which the evaporation of such a film, if not removed, wouldleave.

In the drawings: y

Figure 1 is a vertical view in elevation and in partial section of acomplete layout somewhat diagrammatically illustrated for treatingcontinuous strip in accordance with the principles` of the presentinvention;

Figure 2 is an enlarged front end view in sectional elevation of adetail of the apparatus arrangement of Figure 1;

Figure 2a is a reduced view constituting a con# tinuation of Figure 2and showing an apparatus arrangement for producing suction;

Figures 3-6, inclusive are `somewhat diagrammatic side views inelevation showing details of liquid removing apparatus.

As shown, for example, in Figure l, I may employ a coil or reel 5 ofstrip metal 6. The strip is subjected to a series of cleaning operationsor treatments in compartments Ato E, inclusive,

and is pulled through such compartments or treatment stations at asuitable tension ty a pair of motor driven pinch rolls l. .Aftertreatment, the strip may be recoiled or subjected to other treatments asdesired. The operation of the present apparatus is not limited tointerrupted lengths of strip, b-ut maybe and is preferably employed totreat continuous lengths or coiled lengths that are welded together toform a continuous length.'

The pinch rolls 'I pull the strip past treatment stations at a desiredspeed, provide a tension `suitable to overcome frictional and otherlosses, and maintain the strip` in a substantially` horizontal planeduring its movement and thus during its treatment.

In compartment A, the strip is wet-'brushed or scrubbed on both of itssides by roll and brush pairs I0, I2. Previously-used hot washingsolution or water is applied in any suitable manner-as by jets I3.Thence, clean wash water is applied to both sides of the strip,preferably under a relatively higher pressure, by such means asrjets I4to remove the dirt and grit and the previouslyused washing solution.Finally, the thin film of liquid remaining on the surface portions isremoved by a suction or vacuum cleaningapparatus 30. j b Y 'I'he stripenters compartment `B dry and as clean as hot water scrubbing can makeit and is then subjected to a series of concentrated 40 chemicalcleaning solution sprays I8. Additional sprays 23 apply the chemicalsolution in compartment C while the strip is being brushed and scrubbedby roll-brush pairs 20, 22. Finally, the strip is again washed with aclean washing iluld at Ila and the liquid film removed at 30a. If`desired, the step of washing at Illa may be omitted, and the chemicalsolution instead of Wash water removed at 30a, suitable changes in thepiping system being made to return the chemical solution forre-circulation.

In compartment D, the chemically cleaned strip is subjected to a seriesof suitable applications of clean heated wash or rinsing water by spraysor jets 24. In compartment E, the strip is initially subjected to` acleaning jet or spray to the chemical solution settling tank 5I.

e application at I4b that is preferably of a high i shown somewhatdiagrammatically in Figure 1,

is primarily chosen for the purpose of illustrating the principles ofthe present invention, and it will be apparent that other suitablearrangements may be employed. The compartment A, the compartments B-andC, the compartment D, and the compartment E, have,- as shown, collecting-tanks for the solutionsv or fluids employed in treating the striptherein. I have also provided a water settling tank 50 and a chemicalsolution settling tank 5I that may be employed in a conventional mannerto remove sediment and prepare the liquids for reuse. Although I haveshown representative pumps, heat exchangers, valves, etc., it will beapparent that they may be rearranged and others may be added in accord--ance with the requirements of a given installation. The iloat valveshave been given a common designation a; the `heat exchangers have beengiven the common designation H followed by a suffix; the` pumps havebeen designated PV iollowed by a suffix; and the battling within thetanks 60 and 6I for separating the space into compartments has beenindicated `as j and g, respectively. f r

- Fresh or clean water is supplied through a main 5II and is pumped bypump P4 through heat exchanger H4, line 5I, and heat exchanger H5, line`52,'to the cleanwater sprays or Jets 24. Conden- 'sate from theheat'exchanger H5 ilows by gravity through line 53 to heat exchanger HIthat is employed to heat previously-used wash water which is taken oi!from the wash water settling tank $0 through piping 55 and forced bypump PI through line 55 and sprays I3. The condensate line 53 also has abranch lineA 54 that is providedv with inlets or oric'es b `forsupplying the settling tank il! with warm condensate as needed. v

Wash water or dilute solution used in compartmentA drains o il bygravity through lines 51 and 58 toreturn to the settling tank 50 forreuse. Likewise, liquid taken oil by the vacuum suction apparatus flowsthrough lineI 31 'past suction unit I5 through line 45 to the settlingtank return line 53.

I'he chemical solution sprays IIIy and 23 of compartments B and C aresupplied with chemical cleaning solution by a takeoi 65 from theircommon collecting tank. The pump P2 moves'the takeoff liquid throughheat exchanger H2 and into the spray supply line 65. The levelof thechemical ysolution in the collecting tank of compartments B and C ismaintained by a float valve a and a solution supply line 58. Pump'P3delivers solution from the chemical solution settling tank 5I throughthe line 68 as required.

It will be noted that vacuum cleaning devices 30h of compartment E areconnected through branch line 31h, vacuum unit I5, line 45h, line 1I,and liquid return line 58, to the water'settling tank 50, while thecleaning device 30a is connected through line 31a, -vacuum unit I5, line45a, A branch line 12 from the collecting tank of compartment D isconnected to the washing fluid return line 45h, 1I to supply settlingtank 6I with water as needed to compensate for evaporation losses and ascontrolled by a float valve a.

The water supply line 50 is provided with a branch line 13 thatintroduces clean wash water into the tanks 60 and 5I through upper inletopenings or nozzles d and lower inlet openings or nozzles c.

In Figures 2 and 2A, I have shown a cleaning unit` that may be termed asuction or vacuum unit. An upper suctionv hood 3l is preferablypositioned to extend for substantially the full width of the strip beingmoved and may be provided with a lower cooperating hood 30'. Both hoodsare connectedby flexible conduits 36 to a vacuum line 31 oi vacuum tank38. This tank serves to separate air and vapor from the liquid. Thegases (air and vapor) are drawn out near the top of tank 38 through pipe35 by a motordriven `wet-vacuum pump unit 4l, while the liquid isconstantly removed from the bottom of the tank through pipe 43 by amotor-driven centri!- ugal pump unit 44. Water for sealing the Wet-lvacuum pump is supplied by pipe 42, and the air and vapor are dischargedto the atmosphere through pipe 4 I Pump 44 serves to prevent tank 33from filling with accumulated liquid and to deliver the liquid to thesewer or to return liquid through lines 45, 45a, or 45h to the settlingtanks and 6I.

Other apparatus, such as more elaborate means for separating the liquidfrom the gases combined with a dry vacuum pump, or a. Vfurther liquidand gas separating stage treating the ,exhaust from wet-vacuum pump unit45, may be employed if desired, such substitutions or furtherrefinements being within the scope of the claims;

' ,It will be noted that on Figure 1, I show heated liquid applied tothestrip for washing and treating steps, butthat cold or unheated liquid isapplied at sprays I4, I4a, and |417, prior to the vacuum removal ofliquid by umts 3l, 3la,.and 30h, respectively. These `cold sprays are`not necessary except where hot treating liquids are employed whichwould iiash into vapor when subiected to a vacuum. Removal of the liquidby evaporation, ashas lbeen pointed out previously, is particularlyobjectionable where'th'e solutions contain dissolved solid constituentssuch as salts which then remain on the surface of the strip. If theliquid which is in aqueous solution-is too hot, its vapor pressure isrelatively high and the applicationof suction for theshort period duringwhich the strip is passing the nozzle results in evaporationof thesolution such as water place, withoutappreciably cooling the stripitself,

which remains at substantially the same temperature after passingbetween the suction heads. However, under some conditions, particularlyafter a iinal washing with pure water, evaporation may be desired, inwhich case the cold liquid sprays may be eliminated, or where a coolsolution is used, heat may be applied thereto by suitable heatingelements in the region occupied by the cold sprays shown on Figure l.

As shown in Figure 2, the hood portions 30 or 30 are provided withltransversely-extending brackets 3l that are mounted upon a suitablesupport frame 34 by adjustable'bolt means 32. Springs 33 are held incompression between the frame 311 and the brackets 3| to flexibly mountand support the suction hood portions 30 and30'. The bolt means 32 istightened to compress the spring 33 when the hood is to be moved awayfrom the strip and is loosened to move the hood towards the surface ofthe strip.l

Although in a preferred arrangement, I employ a pair of upper and lowersuction hood portions 30 and 3U', it will be apparent, as shown inFigure 5, for example, that single hood portions may be employed and maybe staggered in such a manner as to aid pinch rolls such as 'la insupporting or holding the strip 6 in a substantially horizontal planeduring its movement.

In the arrangement of Figure 3, I h'ave shown high pressure clean waterjets I4 for washing away the previously used solutions and leaving arelatively thin film of clean solution. This, of course, will lessen theburden of the suction apparatus 3B. In the arrangement of Figure 4, aforward pair of pinch rolls 1b is employed in oooperation with pinch'rolls 1a to hold the strip tightly in position during the suctionoperation. 'I'his arrangement is particularly advantageous to avoiddeection of the strip when an extremely high suction pressure or forceis employed. The rolls 'lb are preferably drawn closely enough todeflect surplus liquid edgewise to either side of the strip, to therebyleave only a very thin film to be removed by the suction unit 30.'

I have found that the speed of the strip should also be considered withreference to the eiectiveness of the lm removal. If under high speedconditions th'e amount of liquid to be removed cannot be taken care ofby one set of suction nozzles, any suitable number of successive nozzlesor suction d evices in sequence may be provided as needed.

In Figure 2 I have shown a representative type of suction nozzlearrangement and it will be apparent that other suitable arrangements maybe employed depending upon particular requirements and the size and typeof impervious material `being cleaned. For example, in Figure 6 I haveshown an anti-friction non-scratching type of shoe 'l0 attached tobottom edge portions of the suction nozzles 30 and 30' of Figure 2 bysuitable brackets 'H and bolts 12. This ligure also illustrates th'enature of the suction action upon the uid film 8. The movement of liquidisolate each cleaning operation to conserve the cleaning fluids and toprevent dilution. The ar-` rangement is such that the liquid illm willbe removed regardless of the speed of the operation and can Ibeaccomplished without the necessity of intermittent pauses. It will beapparent that the strip enters a successive treating station with itssurfaces practically free from liquid film, such that the succeedingoperation can be more effectively accomplished. It will also be apparentthat in such an arrangement where there is no carryover of liquid nlm,the need for additional successive washing applications has beeneliminated as well as the need for additional collecting tanks toprovide a re-use of the material washed of! 'by such successiveapplications. In view of the above considerations, I have been able toeilect a high speed treatment of strip whereby it is cleaned at maximumeffectiveness and at a minimum expense. It will b'e also apparent lthatmy invention is not limited to speciilc apparatus or apparatusarrangements shown, and that various modications, substitutions, andrearrangements may be made without departing from the spirit and scopeof the invention as indicated by the appended claims.

I claim:

l. Apparatusl for cleaning continuously mov-` liquid to the metal. andvacuum instrumentalitiesv for removing substantially completely from themetal all adhering liquid without substantial evaporation thereof fromthe metal, the said carried by the strip is partially arrested uponencountering the shoe 'l0 and the liquid tends to accumulate in such amanner as to prevent contact of the strip with the shoe. YAir enterschiefly from th'e opposite end of the shoe between the shoe and thestrip and has a high velocity. This results in the liquid being arrestedat the suction nozzle and removed from the strip at the nozzle orifice,as somewhat diagrammatically illustrated in Figure 6. For this reason, Ipreferably provide the entry portion of the shoe 10 or the suctionnozzle with a greater clearance on its incoming side than on itsoutgoing side. This provides the outgoing side with a narrow orifice toincrease the effectiveness of the removing action. The larger sizeorifice at the incoming side permits a quick removal of the liquid filmsuch that the greater portion of it is removed before the strip hasmoved past a substantially central point of unit 30.

'I'he hood portions of the suction device 30 are preferably resilientlyor flexibly mounted for independent adjustment and also to preventdamage when any solid material, obstruction, or uneven portion of thestrip moves therepast.

Itv will be apparent from the above description that suction or liquidremoving vacuum units can be employed along the cleaning line to, ineffect,

metal thereby passing into a second treating compartment as clean as themechanical scrubbing can make it. and dry. instrumentalities inthesecond compartment for applying a concentrated-` cleaning solution tothe metal as it moves through the second compartment into a thirdcompartment. mechanism in the third compartment for mechanicallyscrubbing the thus-treated metal as it moves therethrough, meansintermediate the said mechanicallv scrubbing mechanism in the thirdcompartment for applying liquid to the metal as the metal is scrubbed,meansin the said third compartment following `the liquidapplying meansand the mechanically scrubbing mechanism for applying clean wash liquidto the metal. vacuum-drying means in the third com partment for removingsubstantially completely all liquid lm from the metal, the said metalpassing into a fourth compartment dry and as mechanically clean as thescrubbing can make it. means in the fourth compartment for applyingclean wash liquid to the metal, the metal being passed into a iifth. oroutlet. compartment. means in the said fifth compartment for applyingclean wash liquid to the metal under high pressure, and vacuum-dryinginstrumentalities operating on the resulting washed metal to remove allliquid adhering thereto. the metal pass"- ing from the said compartmentdry and in chemically clean condition.

2. Apparatus for cleaning continuously moving indeterminate lengths ofmetal strip from'a coil thereof, which comprises, in combination, a.series of successive treating compartments for the strip, extending froman intake compartment for the strip to an outlet compartment therefor,means for continuously moving the strip through the said compartments,means in the intake compartment for alternately mechanically scrubbingthe moving strip and for applying hot cleaning l0 liquid theretofmeansfor heating the cleaning liquid, means for recirculating the cleaningliquid from the said intake compartment through the heating means,mechanism for. iinally applying clean cold wash liquid to the strip inthe intake 15 compartment, vacuum-drying means for the intakecompartment for closely applying suction to the strip for removingtherefrom substantially all adhering liquid without appreciableevaporation of the `liquid from the strip, the said strip 20 calscrubbing mechanism for applyinghotconcem' tratedcleaning solution tothe strip as the strip is scrubbed, mechanism for continuouslyrecirculating the concentrated cleaning solution through the second andthird compartments, means in the third compartment for rinsing thecleaned and mechanically scrubbed strip with clean, cold wash liquid,vacuum-drying means inthe third compartment for removing by suction at`least substantially all liquid adhering to the strip without anyappreciableevaporation of the liquid, the strip thereby passing dry `andmechanically clean into a fourth compartment, means for washing thestrip in the. fourth compartment with clean hot wash liquid, theresulting cleaned strip passing from the fourth compartment into aIfth'compartment, means in the lifth compartment for spraying the strip withhi'ghl pressure sprays of cold wash liquid, and final vacuum-drying.

means in the fifth compartment for removin all adhering liquid from thestrip. q y

GEORGE Ml; caor'r.

